<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div id="app">
        <div class="item">
            <label for="email">Email</label>
            <!-- 邮箱的规则：
              1、不能为空
              2、有且只有一个@
              3、.符号只能出现在@之后 @126. @qq.
              4、域名的后缀[.com,.com.cn,.net,.cn,.edu.cn]
             -->
            <input id="email" name="email" type="email" placeholder="输入邮箱地址" />
            <span id="email-check">*</span>
        </div>
        <button id='submit'>Login</button>
    </div>

</body>
<script src="../js/demo.js"></script>

</html>